Neurologic disorders of aging

K K Jain MD (Dr. Jain is a consultant in neurology and has no relevant financial relationships to disclose.)Originally released November 19, 1998; last updated September 12, 2018; expires September 12, 2021

This article includes discussion of neurologic disorders of aging, geriatric neurology, gerontologic neurology, and neurology of aging. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

This article reviews the changes in the brain that occur with aging and their manifestations. Some of the neurologic disorders that are more common in the elderly are already covered in various other MedLink Neurology articles. Some of the lesions observed in the brains of the elderly do not necessarily manifest clinically unless a certain threshold is reached. The distinction between healthy aging and dementia is discussed. Although changes in the brain that are associated with aging cannot be prevented, the onset of the impairment of function can be delayed, and neuropsychological performance can be improved by certain measures, including mental and physical exercises. Future strategies based on advances in molecular neurology are also considered.

Key points

• Some neurologic disorders are more common in the elderly, and their prevalence is increasing with higher life expectancies.

• Neuroanatomical, neurophysiological, neurochemical, and neuropsychological aspects of aging need to be studied to understand the clinical manifestations of neurologic disorders of the elderly and to differentiate them from normal aging.

• There is some evidence that mental and physical exercise can reduce cognitive decline associated with aging.

• In addition to pharmacotherapy, neurorehabilitation is important in the management of neurologic disorders of the elderly, with an emphasis on gait training.

Historical note and terminology

Neurologists in the 19th century were not interested in disorders of aging because life expectancy was low. Their interests were limited to 2 disorders associated with aging: Parkinson disease and stroke. Even in the year 1900, life expectancy in the United States was 49 years; there were only 3 million persons older than 65 years and 72,000 persons older than 85 years. By 1996, life expectancy had increased to 78 years, and there were 33.3 million persons older than 65 years and 2.2 million persons older than 85 years (Katzman 1998).

Berger, in reporting his discovery of brain waves, described age differences in EEG parameters (Berger 1929). In 1931, the first article appeared on neurology of aging (Critchley 1931). Alzheimer disease has received increasing attention during the past 2 decades, and several other diseases associated with aging are now the focus of neurologists' attention. Neurology of aging, also called geriatric neurology, is becoming increasingly important. The number of people who are 65 years or older is growing twice as fast as the whole population. The number of those who are 85 years or older is growing 5 times as fast. By the year 2050, life expectancy should reach 85 years, and the population older than 95 years will increase to more than 1 million. By the end of 21st century, life expectancy may well reach into the 90s.

No satisfactory classification of aging exists. The World Health Organization terminology for the aging process is as follows:

• 51 to 60 years: aging persons
• 61 to 75 years: elderly persons
• 76 to 90 years: aged persons
• 91 to 100 years: very old persons
• 100 years and over: long-lived persons
• The age limit of 65 years arbitrarily marks the beginning of old age. This corresponds with the age of retirement in most countries.

Biological age does not always correspond to chronological age. Premature aging may lead to an onset of neurologic disorders before a person has reached the age of 65 years.

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